DARPA's New Chip Will Supercharge Radar Defenses

Last week, the Defense Research Projects Agency (DARPA) announced it had developed a new semiconductor chip to could ensure the uninterrupted operation of military communications and radar. It's an exceptionally high-speed analog-to-digital converter (ADC), to be precise.

Media outlets including the Washington Post praised DARPA's advance as one that "will create unjammable communication devices." That's not exactly right. While DARPA's achievement is impressive, it doesn't yet mean unjammable communications devices. What it does do is quickly translate analog radio frequency signals (RF) into a digital format.

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Once an analog signal is digitized, specialized electronic surveillance software can analyze it, determining whether the signal is from a friendly or hostile radar or communications source, where it's located, and whether it's real or fake.

"It enables sampling and data acquisition from larger portions of the spectrum."

ADCs are used commercially in mobile devices and desktop computers to digitize analog sound for voice communication or recording. Television tuner cards use ADCs to convert broadcast signals from analog to digital and the military uses ADCs to secure and classify radar and other sensor signals.

But today's ADCs can process data only within a limited portion of the electro-magnetic (EM) spectrum at a given time. As a result, they intermittently miss critical information about radar, jamming, communications, and other problematic EM signals. DARPA's goal with this new chip was to expand the volume of data that can be processed and analyzed by developing an ADC with a processing speed nearly ten times that of commercially available alternatives.

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The resulting ADC chip, built in conjunction with GlobalFoundries, samples and digitizes spectrum signals at a previously unachievable rate of more than 60 billion times per second. Such speed confers the ability to sample signals from a much wider spectrum range, providing more bulk data for threat management software to analyze, prioritize, and filter. Think of DARPA's new ADC as a bigger butterfly net.

"The primary advance of the new ADC chip is that it enables sampling and data acquisition from larger portions of the spectrum than other chips of its kind," Troy Olsson, program manager at DARPA's Microsystems Technology Office, says. "This means it could provide better overall situational awareness of the RF-based threats in contested environments."

Plus, the new ADC chip allows many of the subsequent signal processing functions to be realized in the digital domain, where they can be adapted using software and firmware. For example, scanning thousands of radar, communications and electronic warfare signals currently requires costly application-specific hardware with long development cycles. Despite sampling up to a terabyte per second of data, the new ADC can process signals itself, reducing the amount of data that must be communicated to neighboring electronics. The digital processing capabilities can also be upgraded at the pace of modern software.

"The application of such high-speed data converter technology is only beginning to be explored," Olsson says.

Olsson points out that high-power energy bursts are more of an issue for an overall system design, not just the design of a component, such as an ADC chip. But power is a problem for the new ADC. It requires so much that it cannot currently be integrated into small systems or portable devices. That means platforms like tactical aircraft and vehicles and small communications devices and command/control systems may not be able to benefit from the speedy ADC. While the current technology is suitable for some applications Olsson acknowledges, "Future generations will be able to handle higher power levels and will thus be applicable to an increasing number of systems."

If DARPA can leverage smaller transistor technology, building chips using new 14-nanometer processes, ADC power efficiency could increase by as much as 50 percent. Super-fast ADCs still won't eliminate effective EW but they'll surely make it harder for our adversaries.

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